1. Field of the Invention
The invention relates to a method for regulating the transmission power of a transmitter system incorporated in an electronic module of an automobile. It extends to an electronic module for implementing this regulation method.
2. Description of the Related Art
More and more automobiles have electronic systems such as systems for monitoring operating parameters of members of the vehicle, or access systems for locking and unlocking the openings of said vehicle.
These electronic systems conventionally comprise electronic modules, a central processor unit installed in the vehicle, and transmission means associated with the central processor unit and incorporated in each electronic module and designed to enable a dialog between said central processing unit and said electronic module in order to implement a given application.
Examples of monitoring systems thus include the systems for monitoring operating parameters of wheels of a vehicle, comprising, mounted on each of said wheels, an electronic module incorporating an electrical power supply battery, a microprocessor, a transmitter system, and sensors dedicated to measuring parameters, such as pressure or temperature of the tires fitted on these wheels, and intended to enable the driver to be informed of any abnormal variation of the measured parameter.
One of the problems encountered in the operation of such monitoring systems lies in the wide dispersion, for electronic modules of one and the same type, of the transmission powers of the transmitter systems, which may, for a conventional type of electronic module intended to be mounted on a vehicle wheel, vary over a range of the order of 6 dB between a maximum power obtained with a new battery and components that have a high nominal power, and a minimum power obtained with a weak battery and components that have a low nominal power.
Because of this dispersion, in practice, and firstly, the transmission power must be raised, which directly penalizes the electrical consumption and the size and the cost of the various components (battery, etc.).
Furthermore, each additional decibel on the tolerances has direct repercussions on the parameters of the monitoring system: margin needed to allow for the location of the wheels for a system monitoring operating parameters of said wheels, surface area of the zone covered around the vehicle for systems for accessing said vehicle, etc.
These data make the use of the electronic modules of the current monitoring systems restrictive.